Three aspects of the project have been examined: 1) Four ways of changing the lipid composition of plasma membrane vesicles have been explored in a preliminary way: a) Phospholipid exchange proteins (PLEP) were isolated from rat liver and various combinations of PLEP, plasma membrane vesicles and artificial lipid vesicles were incubated and isolated on sucrose gradients. No significant change in plasma membrane vesicle density was observed. b) Plasma membrane vesicles were treated with excess lipid in the presence of detergent, the removal of which proved difficult by centrifugation and dialysis. c) Acetone depletion of lipids and restoration of exogenous lipids was also tried but it was unclear whether actual incorporation or adhesion of lipid occurred. d) Attempts at osmotically shocking adherent vesicles in order to cause their fusion did not succeed. 2) Isolation and characterization of boundary lipid has been attempted by treating plasmamembrane vesicles in various states of protein depletion with a variety of solvents. 3) 3T3 an SV3T3 cell have been grown and plasma membrane vesicles isolated therefrom purpose of altering their lipid compositions and for the isolation of boundary lipid therefrom.